Microscopic measurements of deformation of liquid surfaces induced by localized direct current electric field.

This study presents a new microscopic method for the measurements of the deformation of liquid surfaces induced by a localized direct current (dc) electric field in a noncontact manner. Since the dielectric constant of aqueous and organic liquids is larger than that of air, the liquids tend to occupy a space with a stronger electric field. The horizontal level of transparent surfaces was measured with a constructed microscopic system that possessed a resolution of about 2 microm. When a rod electrode (2.0 mm in radius) was brought near to a liquid surface vertically within 150 - 200 microm and a dc voltage (50 - 75 V) was applied, the surface just under the electrode rose by 4 - 19 microm. The deformation of the liquid surfaces was quantitatively analyzed by using a dielectric force, surface tension, and hydrostatic pressure.